LTFT and STFT question on data logging (SCT)

jjandascog · 04-11-2007, 12:31 PM

Does anybody know if you are supposed to add .5 to the data logged value for Long Term Fuel Trim. The instructions that came with my SCT Xcal said you are supposed to but on the SCTflash site they say you are not supposed to. I called SCT and they said that there instructions are incorrect but the guy I spoke to did not seem real sure of him self.

I ask because I am trying to stop my 93 tune from pinging under part load and WOT. It has bad tip-in pinging form 40 to 60mph. American Muscle has sent me 4 tunes that have gotten progressively better but the pinging is still there.

I have included a chart of the latest data logging, and I have added .5 to the LTFT as the instruction say. This looks way lean which might be the problem if I am supposed to add .5 to the logged reading. If I am not supposed to add .5 then the LTFT looks good.

R3dn3ck, have you seen data like this? ( I ask b/c I see that you are doing your own tunes)

P.S Sorry for the long post

*03gtmustang* · 04-11-2007, 12:51 PM

Pretty sure you ARE supposed to add .5.

jjandascog · 04-11-2007, 01:52 PM

Dang in that case I am running real lean, no wonder I am pinging

r3dn3ck · 04-11-2007, 03:35 PM

do you know the total timing anywhere (or everywhere) in that run? In any case if you're running lean on part throttle you'll need to do some tinkering. I haven't yet had to stray too far away from the canned tunes that came with the pro-racer kit. Some minor tweaks here and there but I've been fortunate enough to steer clear of much in the way of having to datalog anything. I got the AF dialed in with just a little hand curving of the MAF xfer, some tiny timing adjustments and all the usual BS for the adaptive unfugging.

jjandascog · 04-12-2007, 06:07 AM

Here is a chart of the spark vs rpm for the same run. I do not have pro-racer yet but it looks like I need to get it so I can control more parameters

04-11-2007, 12:51 PM	#2 (permalink)
03gtmustang Super Moderator Join Date: Jan 2005 Location: Northern Va Posts: 3,244	Pretty sure you ARE supposed to add .5. __________________ D&D Auto Detailing -Dan

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04-11-2007, 01:52 PM	#3 (permalink)
jjandascog Junior Member Join Date: Jan 2007 Posts: 17	Dang in that case I am running real lean, no wonder I am pinging

04-11-2007, 03:35 PM	#4 (permalink)
r3dn3ck Wowbagger hates me too! Join Date: Nov 2005 Location: Magrathea/California Posts: 7,008	do you know the total timing anywhere (or everywhere) in that run? In any case if you're running lean on part throttle you'll need to do some tinkering. I haven't yet had to stray too far away from the canned tunes that came with the pro-racer kit. Some minor tweaks here and there but I've been fortunate enough to steer clear of much in the way of having to datalog anything. I got the AF dialed in with just a little hand curving of the MAF xfer, some tiny timing adjustments and all the usual BS for the adaptive unfugging.